Magnetic alloy



Patented Dec. 24, 1929 UNITED STATES PATENT OFFICE WILLOUGHBY STATHAMSMITH, OF NEWTON POPPLEFORD, HENRY JOSEPH GAR NETT, OF SEVENOAKS, ANDJOHN ANGEL HOLDEN, F GIDEA PARK, ENGLAND MAGNETIC ALLOY No Drawing.Application filed November 2, 1927, Serial No. 230,688, and in GreatBritain November 6, 1926.

This invention relates to quaternary alloys and their application totelegraphic and telephonic conductors.

The alloys in question comprise nickel and iron, a third element whichis either silicon or aluminium, and a fourth element, preferably eitherchromium, tungsten, molybdenum or vanadium.

The objects of the invent-ion are alloys of high electrical resistanceand high magnetic permeabilities in fields of H from .001 gauss to 2gauss.

Alloys are known which have high electrical resistance and initialpermeability of the order of 1000 and in the known alloys nickel is thechief constituent. In the alloys described herein, iron is the majorconstituent and these possess initial permeabilities of a higher order,so that not only are they superior in magnetic properties to the knownalloys, but

they are also less costly to manufacture.

According, to this invention an alloy comprises nickel 3242%, the saidthird and fourth elements, each of which may vary between 1 1% of thewhole, and the remainder iron, which is, however, preferably within thelimits 5565%.

Such alloys possess very high electrical resistance, and magneticpermeabilities which are practically constant within fields between .001and .100 gauss and do not vary more than 10%.

' Carbon should be substantially excluded, but to promote workability, asmall content amounting to not more than a few tenths of 1% of manganeseor other metal having deoxidizing properties may be added. Substances ofthis class will be hereinafter included in the term a deoxidizer of theman 40 ganese type. A quantity as great as 1% is not desirable, andexcellent results have been secured with the addition of only 3%.

As a result of many experiments we have found alloys which, when rolledinto strip,

or drawn into wire, etc., and suitably heat treated have propertieswhich make them suitable for loading submarine telegraph conductors forduplex working.

Example 1 Per cent Iron 60.0 Nickel 36.5 Chromium 2.0 Silicon 1.3Manganese .2

after forging, drawing the wire and heat treating rapidly to 900 C. innitrogen, maintaining at that temperature for two minutes, and coolingin air, had the following magnetic properties H=.001 =1580 H=.05 =1650H=.1O =1675 Its electrical resistance was 95 microhms per cm.

In order to secure the foregoingresults the raw materials used in themanufacture of the alloy were of good quality. Swedish charcoal ironcontaining only 04% of carbon was used as a base. Mond nickel andchromium prepared by the thermit process were melted with the iron; thesilicon addition which took the form of 95% ferro silicon, was addedtogether with the manganese immediately prior to casting. The meltingwas carried out in an induction type of furnace, the subsequentoperations for forging, rolling, etc., were carried out by the usualmethods.

A signalling conductor loaded with wire of the foregoing composition,after heat treatment, when tested with an alternating current of between1 and 100 milliamperes, had an inductance that only varied 8%.

Cir

Example 2.An alloy containing Per cent Iron 60.0 Nickel 36.5 5 Chromium1.9 Silicon 1.3 Manganese .3

after forging, drawing to wire and annealing at 900 C. for two minutes,has an electrical resistance of 95 microhms per 0111 and the followingmagnetic properties I-I- .001 1500 H= .01 -1600 1 H- .10 .=1770 H==1.0=4780 When aluminium is the third element, themagnetic permeabilityshows greater variation within the limits of a field between .001 and.100 gauss. For example, an alloy containing:

' Per cent Iron 58 Nickel 36 Chromium 3 Aluminium 3 after reducing towire, and heat'treating as 1-4% of aluminum, 1-4% of an element forincreasing the electrical resistance, and iron the remainder.

2. A' magnetic material substantially free from carbon comprising nickel32-42%, iron 55-65%, 1-4%'of aluminum and 1-4% of an element forincreasing the electrical resistance.

' 3. An alloy as claimed in claim 1, comprising not more than 1% of a'deoxidizer such as manganese.

4. A magnetic material substantially free from carbon comprising nickel32-42%, iron -65%, 1-4% of aluminum, 1-4% of an ele- 55 ment forincreasing the electrical resistance,

from carbon comprising nickel 32-42%, iron 55-65%, 1-4% of aluminum, and1-4% of chromium.

8. Quaternary alloys of iron and nickel, comprising nickel 32-42%, iron55-65%, aluminium 1-4%-, 1-4% of chromium, and not more than 1% of adeoxid'lzer such as manganese.

9. A magnetic material substantially free from carbon comprising about32 to 42% of nickel, about 55 to of iron, about 1 to 4% of a substanceselected from the group consisting of silicon and aluminum, and about 1to 4% of a substance selected from the group consisting of chromium,tungsten, molybdenum and vanadium, such alloy containing no more than afew tenths of a per cent of manganese.

10. A magnetic material substantially free from carbon comprising about32 .to 42% of nickel, about 55 to 65% of iron, about 1 to 4% of asubstance selected from the group consisting of silicon and aluminum,and about 1 to 4% of a substance selected from the group consisting ofchromium, tungsten, molybdenum and .vanadium,-and containing a fewtenths of a per cent only of a deoxidizer of the manganese type.

11. A magnetic material substantially free from carbon comprising about32 to 42% of nickel, about 55 to 65% of iron, about 1 to 4% of asubstance selected from the group consisting of silicon and aluminum,and about 1 to 4% of a substance selected from the group consisting ofchromium, tungsten, molybdenum and vanadium, the said alloy beingsubstantially free of carbon, such alloy containing no more than a fewtenths of a per cent of manganese. V

In testimony that we claim the foregoing as our invention, we havesigned our names this twenty fourth day of October, 1927.

WILLOUGHBY STATHAM SMITH.

HENRY JOSEPH GARNETT. JOHN ANGEL HOLDEN.

and not more than 1% of a deoxidizer such as manganese.

5. A magnetic material substantially free from carbon comprising iron58%, nickel 60 36%, chromiunf f' -3.%, aluminium 3%.

- 6. A magnetic'Jmaterial\substantially free from carbon comprisingnickel 32-42%, 1-4% of aluminum, chromium 1-4% and iron the remainder.

' 65 7 A magnetic material substantially free

